This invention relates generally to heat exchangers and, more particularly, to a microchannel heat exchanger having multiple port extrusions and a bent configuration.
Refrigerant vapor compression systems are well known in the art. Air conditioners and chillers employing refrigerant vapor compression cycles are commonly used for cooling, or both cooling and heating air supplied to a climate controlled zone of a building. Conventionally these refrigerant vapor compression systems include a compressor, condenser, and expansion device, and an evaporator connected in refrigerant flow communication to form a closed refrigerant circuit.
In some refrigerant vapor compression systems, one of the condenser and the evaporator is a parallel tube heat exchanger. Such heat exchangers have a plurality of parallel refrigerant flow paths provided by a plurality of tubes extending in parallel relationship between an inlet header and an outlet header. Flat, rectangular, or oval shape multichannel tubes are commonly used. Each multichannel tube has a plurality of flow channels extending longitudinally in parallel relationship over the length of the tube, each channel providing a small cross-sectional flow area refrigerant flow path. An inlet header receives refrigerant from the refrigerant circuit and distributes that refrigerant flow amongst the plurality of flow paths through the heat exchanger. The outlet header collects the refrigerant flow as it leaves the respective flow paths and directs the collected flow back to the refrigerant vapor compression system.
In certain applications, the parallel tube heat exchanger is required to fit into a particularly sized housing to minimize the footprint of the air conditioning system. In other applications, the parallel tube heat exchanger is required to fit into an airflow duct of a particular size. In such instances, it may be necessary to bend or shape the parallel tube heat exchanger to accommodate these restrictions while ensuring an undiminished ability to cool or heat the climate controlled zone. One practice of bending and shaping parallel tube heat exchangers involves bending the heat exchange assembly around a cylinder. During this process, force is applied to one side of the assembly to wrap it around a partial turn of the cylinder to provide a uniform and reproducible method of bending the assembly.
One problem with this method is that composite multiport extruded (MPE) microchannel heat exchangers are significantly stiffer, and therefore more difficult to bend than regular MPE multichannel heat exchangers. In addition, newer refrigeration systems having a larger capacity may require a compound heat exchanger construction, which resembles two slabs arranged side by side and joined at the ends. This kind of construction cannot be easily bent without major damage unless large bend radii are used, which results in the heat exchanger being too large to fit within the desired sizing envelope.